Inc. Network Card User Manual

130 www.xilinx.com 1-Gigabit Ethernet MAC v8.5 User Guide

UG144 April 24, 2009

Appendix A: Using the Client-Side FIFO

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Overview of LocalLink Interface

Data Flow

Data is transferred on the LocalLink interface from source to destination, with the flow

being governed by the four active low control signals sof_n, eof_n, src_rdy_n, and

dst_rdy_n. The flow of data is controlled by the src_rdy_n and dst_rdy_n signals.

Only when these signals are asserted simultaneously is data transferred from source to

destination. The individual packet boundaries are marked by the sof_n and eof_n

signals. For more information on the LocalLink interface see to Xilinx Application Note

XAPP691

, “Parameterizable LocalLink FIFO” available at

direct.xilinx.com/bvdocs/appnotes/xapp691.pdf

Figure A-2 shows the transfer of an 8-byte frame.

Figure A-3 illustrates frame transfer of a 5-byte frame, where both the src_rdy_n and

dst_rdy_n signals are used to control the flow of data across the interface.

Figure A-2: Frame Transfer across LocalLink Interface

Figure A-3: Frame Transfer with Flow Control

clock

data[7:0]

sof_n

eof_n

src_rdy_n

dst_rdy_n